Thrust sliding bearing

ABSTRACT

A thrust sliding bearing  1  includes: a synthetic resin-made upper casing  2 ; a synthetic resin-made lower casing  3  which is superposed on the upper casing  2  so as to be rotatable about an axis O in a circumferential direction R relative to the upper casing  2 ; a synthetic resin-made thrust sliding bearing piece  5  disposed in an annular space  4  between the upper casing  2  and the lower casing  3 ; and a synthetic resin-made seal member  8  for sealing respective other end portions, communicating with the outside, of a gap  6  on an inner peripheral side and a gap  7  on an outer peripheral side in a radial direction A between the upper casing  2  and the lower casing  3 , the gap  6  and the gap  7  respectively communicating with the annular space  4  at their one annular end portions.

This application is a divisional of Ser. No. 13/814,328 filed Feb. 5,2013 which in turn is a U.S. national phase of International ApplicationNo. PCT/JP2011/003406 filed 15 Jun. 2011 which designated the U.S. andclaims priority to JP 2010-178215 filed 6 Aug. 2010, the entire contentsof each of which are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to a synthetic resin-made thrust slidingbearing, and more particularly to a thrust sliding bearing which issuitably incorporated as a thrust sliding bearing of a strut-typesuspension (Macpherson type) in a four-wheeled motor vehicle.

BACKGROUND ART

In Patent Document 1, a synthetic resin-made sliding bearing is proposedwhich includes a synthetic resin-made lower casing, a syntheticresin-made upper casing superposed on this lower casing, and a syntheticresin-made sliding bearing means interposed between the upper and lowercasings, the synthetic resin-made sliding bearing comprised of an outerresiliently sealing means disposed on an outer peripheral side betweenthe upper and lower casings and an inner resiliently sealing meansdisposed on an inner peripheral side between the upper and lowercasings. In Patent Document 2, a synthetic resin-made sliding bearing isproposed which includes a synthetic resin-made lower casing, a syntheticresin-made upper casing superposed on this lower casing, and a syntheticresin-made thrust sliding bearing member disposed in a space between theupper and lower casings, the synthetic resin-made sliding bearingcomprised of an outer sealing means disposed on an outer peripheral sidein the space between the upper and lower casings and an inner labyrinthsealing means disposed on an inner peripheral side in the space betweenthe upper and lower casings. In Patent Document 3, a syntheticresin-made sliding bearing is proposed which includes a syntheticresin-made lower casing, a synthetic resin-made upper casing superposedon this lower casing, and a synthetic resin-made sliding bearing meansinterposed between the upper and lower casings, the synthetic resin-madesliding bearing comprised of a resiliently sealing means which isdisposed in such a manner as to cover an outer surface of the lowercasing and which seals outer and inner annular openings of a spacebetween the upper and lower casings at both annular end portions. InPatent Document 4, a synthetic resin-made sliding bearing is proposedwhich includes an upper casing having an annular lower surface, a lowercasing which is superposed on this upper casing so as to be rotatableabout an axis of the upper casing and has an annular upper surface, andan annular thrust sliding bearing piece disposed in an annular spacebetween the annular lower surface and the annular upper surface, thesliding bearing comprised of a sealing means disposed on at least oneside of an outer peripheral side and an inner peripheral side of theannular space. Furthermore, in Patent Document 5, a synthetic resin-madesliding bearing is proposed which includes a synthetic resin-made uppercasing having an annular lower surface, a synthetic resin-made lowercasing having an annular upper surface, and a thrust sliding bearingpiece disposed in an annular gap between the annular lower surface andthe annular upper surface.

PRIOR ART DOCUMENTS Patent Documents

-   -   [Patent Document 1] JP-A-2001-27227    -   [Patent Document 2] JP-A-2001-27228    -   [Patent Document 3] JP-A-2001-27229    -   [Patent Document 4] JP-A-2007-303643    -   [Patent Document 5] JP-A-2009-250278

SUMMARY OF THE INVENTION Problems that the Invention is to Solve

Incidentally, with the sliding bearing of Patent Document 1, in order toseal respective gaps on the inner and outer peripheral sides between theupper and lower casings, the inner resiliently sealing means and outerresiliently sealing means which are separate members are disposed in therespective gaps, so that time is required in the assembly operation andtherefore there is a possibility of causing a rise in the manufacturingcost. With the sliding bearing of Patent Document 2, since the labyrinthsealing means is used to seal the inner gap between the upper and lowercasings, the characteristic of preventing the ingress of dust and muddywater from the gap on the inner peripheral side is slightly inferior incomparison with the resiliently sealing means. With the sliding bearingof Patent Document 3, since the resiliently sealing means for sealingthe respective gaps on the inner and outer peripheral sides between theupper and lower casings is disposed on an outer surface of the lowercasing, there is a possibility of the resiliently sealing means comingoff from the lower casing when used over extended periods of time. Withthe sliding bearing of Patent Document 4, in order to seal respectivegaps on the inner and outer peripheral sides between the upper and lowercasings, the inner resiliently sealing means and outer resilientlysealing means which are separate members are disposed in the respectivegaps, so that time is required in the assembly operation and thereforethere is a possibility of causing a higher cost in the same way as thesliding bearing of Patent Document 1. With the sliding bearing of PatentDocument 5, since the labyrinth sealing means is used to seal therespective gaps on the inner and outer peripheral sides between theupper and lower casings, the characteristic of preventing the ingress ofdust and muddy water from the gaps on the inner and outer peripheralsides is slightly inferior in comparison with the resiliently sealingmeans. None of these sliding bearings are yet satisfactory concerningthe manufacturing cost, durability, and sealability.

The present invention has been devised in view of the above-describedaspects, and its object is to provide a thrust sliding bearing whichexcels in the assembling efficiency and replaceability, makes itpossible to reduce the manufacturing cost, and is capable of furtherimproving the durability and sealability.

Means for Solving the Problems

A thrust sliding bearing in accordance with the present inventioncomprises: a synthetic resin-made upper casing integrally including anannular upper casing base portion having an annular lower surface in anaxial direction, an inner peripheral-side suspended cylindrical portionsuspended from a radial inner peripheral end portion of the annularlower surface of the upper casing base portion, and an outerperipheral-side suspended cylindrical portion suspended from a radialouter peripheral end portion of the annular lower surface of the uppercasing base portion; a synthetic resin-made lower casing integrallyincluding an annular lower casing base portion having an annular uppersurface in the axial direction and superposed on said upper casing so asto be rotatable about an axis relative to said upper casing and anannular protrusion protruding from the annular upper surface of thelower casing base portion toward the annular lower surface of the uppercasing base portion; a synthetic resin-made thrust sliding bearing piecedisposed in an annular space between the annular lower surface of theupper casing base portion and the annular upper surface of the lowercasing base portion, so as to be brought at an axial annular uppersurface and a radial cylindrical inner peripheral surface thereof intoslidable contact with the annular lower surface of the upper casing baseportion and a radial outer peripheral surface of the innerperipheral-side suspended cylindrical portion, while being brought at anaxial annular lower surface and a radial cylindrical outer peripheralsurface thereof into contact with an axial annular upper surface and aradial cylindrical inner peripheral surface of the annular protrusion;and a synthetic resin-made seal member having on a radial innerperipheral side thereof a flexible inner peripheral-side annular sealportion which is brought into contact with a radial inner peripheralsurface of the inner peripheral-side suspended cylindrical portion ofthe upper casing so as to seal a gap between the inner peripheral-sidesuspended cylindrical portion of the upper casing and the lower casingbase portion of the lower casing, having on a radial outer peripheralside thereof a flexible outer peripheral-side annular seal portion whichis brought into contact with an radial inner peripheral surface of theouter peripheral-side suspended cylindrical portion of the upper casingso as to seal a gap between the outer peripheral-side suspendedcylindrical portion of the upper casing and the lower casing baseportion of the lower casing, and having a plurality of connectingportions arranged by being spaced apart from each other in a directionabout the axis, so as to connect to each other the inner peripheral-sideannular seal portion and the outer peripheral-side annular seal portion,wherein each of the plurality of connecting portions is passed betweenthe thrust sliding bearing piece and the annular protrusion of the lowercasing and is integrally connected at one end portion thereof to theinner peripheral-side annular seal portion and at another end portionthereof to the outer peripheral-side annular seal portion.

According to the thrust sliding bearing in accordance with the presentinvention, each of the plurality of connecting portions is integrallyconnected at its one end portion to the inner peripheral-side annularseal portion and at its other end portion to the outer peripheral-sideannular seal portion, so that the number of parts can be reduced, andthe assembling efficiency and the replaceability are made to excel,making it possible to attain a reduction in the manufacturing cost.Moreover, since each of the plurality of connecting portions is passedbetween the thrust sliding bearing piece and the annular protrusion ofthe lower casing, the durability can be improved by eliminating thepossibility of coming off. In addition, since the seal member has theinner peripheral-side annular seal portion and the outer peripheral-sideannular seal portion for sealing the gaps between the innerperipheral-side suspended cylindrical portion of the upper casing andthe lower casing base portion of the lower casing on the radial innerperipheral side and outer peripheral side, the sealability can befurther improved.

In a preferred example of the thrust sliding bearing in accordance withthe present invention, each of the connecting portions of said sealmember has a radial connecting portion which is integrally connected atone radial end portion thereof to the outer peripheral-side annular sealportion and an axial connecting portion which is integrally connected atone axial end portion thereof to another radial end portion of theradial connecting portion and at another axial end portion thereof tothe inner peripheral-side annular seal portion, wherein the annularprotrusion of said lower casing has upper surface grooves which arearranged on an axial upper surface thereof by being spaced apart fromeach other in a direction about the axis and receive respective ones ofthe radial connecting portions of the connecting portions and innerperipheral surface grooves which are arranged on a radial innerperipheral surface thereof by being spaced apart from each other in thedirection about the axis and connected to respective ones of the uppersurface grooves and receive respective ones of the axial connectingportions of the connecting portions, wherein the upper surface of theannular protrusion of the lower casing excluding the upper surfacegrooves is positioned flush with or higher than an axial upper surfaceof the radial connecting portion of the connecting portion, and theinner peripheral surface of the annular protrusion of the lower casingexcluding the inner peripheral surface grooves is positioned flush withor radially inwardly of a radial inner side surface of the axialconnecting portion of the connecting portion, and wherein said thrustsliding bearing piece has a radial bearing piece portion which is incontact with the upper surface of the annular protrusion of the lowercasing and an axial bearing piece portion which is in contact with theinner peripheral surface of the annular protrusion of the lower casing.

In the thrust sliding bearing of this example, the radial bearing pieceportion may be in contact with the upper surface of the annularprotrusion of the lower casing and the upper surface of the radialconnecting portion of the connecting portion, and the axial bearingpiece portion may be in contact with the inner peripheral side surfaceof the annular protrusion of the lower casing and the inner side surfaceof the axial connecting portion of the connecting portion.Alternatively, the radial bearing piece portion may be in contact withthe upper surface of the annular protrusion of the lower casing whilehaving a gap with the upper surface of the radial connecting portion ofthe connecting portion, and may be in contact with the inner peripheralsurface of the annular protrusion of the lower casing while having a gapwith the inner side surface of the axial connecting portion of theconnecting portion.

In another preferred example, the annular protrusion has an annularnotched stepped portion on a radial outer peripheral portion of theupper surface thereof, and the flexible outer peripheral-side annularseal portion has an annular outer peripheral seal base portion which isintegrally connected at a radial inner peripheral end portion thereof toa radial outer end portion of the radial connecting portion and isfitted to the notched stepped portion and a flexible outer peripheralseal portion which is connected at a radial inner peripheral end portionthereof to a radial outer peripheral end portion of the outer peripheralseal base portion and is brought into contact with an inner peripheralsurface of the outer peripheral-side suspended cylindrical portion ofthe upper casing. The outer peripheral seal portion extends diagonallydownwardly from the inner peripheral end portion which has a smalleraxial thickness than the axial thickness of the outer peripheral sealbase portion and which is connected to the radial outer peripheral endportion of the outer peripheral seal base portion.

The lower casing has integrally with the lower casing base portion anannular inner peripheral-side protrusion protruding from a radial innerperipheral portion of the annular upper surface of the lower casing baseportion toward an annular lower surface of the upper casing base portionso as to form a inner peripheral-side annular recess in cooperation withthe inner peripheral surface of the annular protrusion, and the innerperipheral-side annular seal portion has an annular inner peripheralseal base portion which is integrally connected at a radial outerperipheral end portion thereof to an axial lower end portion of theaxial connecting portion and which is fitted to the innerperipheral-side annular recess, as well as a flexible inner peripheralseal portion which is connected at a radial outer peripheral end portionto a radial inner peripheral end portion of the inner peripheral sealbase portion and which is brought into contact with the outer peripheralsurface of the inner peripheral-side suspended cylindrical portion ofthe upper casing. The inner peripheral seal portion may extenddiagonally downwardly from the outer peripheral end portion which has asmaller axial thickness than the inner peripheral seal base portion andwhich is connected to the radial inner peripheral end portion of theinner peripheral seal base portion.

The upper casing may have an annular seat portion formed integrally on aradial central portion of an axial annular upper surface of the uppercasing base portion.

In a preferred example, the inner peripheral-side suspended cylindricalportion has a thick-walled cylindrical portion connected at its axialupper end portion to the radial inner peripheral end portion of theannular lower surface of the upper casing base portion, as well as athin-walled cylindrical portion which is connected at its axial upperend portion to an axial lower end portion of the thick-walledcylindrical portion and is thinner-walled relative to the thick-walledcylindrical portion. The inner peripheral-side annular seal portion isin contact with a radial cylindrical inner peripheral surface of thethin-walled cylindrical portion, and the outer peripheral-side suspendedcylindrical portion includes a cross-sectionally trapezoidal cylindricalportion which is connected at its axial upper end portion to a radialouter peripheral end portion of the annular lower surface of the uppercasing base portion and has an inner peripheral surface which isgradually enlarged in diameter as viewed in the axial direction awayfrom the annular lower surface of the upper casing base portion, as wellas an enlarged cylindrical portion which is connected at its axial upperend portion to an axial lower end portion of the cross-sectionallytrapezoidal cylindrical portion and has an inner peripheral surfacewhich is gradually reduced in diameter as viewed in the axial directionaway from the axial lower end portion of the cross-sectionallytrapezoidal cylindrical portion and is gradually enlarged in diameter asviewed in the direction away from this reduced-diameter end, the outerperipheral-side annular seal portion being in contact with thecross-sectionally trapezoidal cylindrical portion.

In a preferred example, the annular protrusion has an arcuate recessedouter peripheral surface which is connected at its axial lower endportion to an outer peripheral end portion of the annular upper surfaceof the lower casing base portion and is gradually reduced in diameter asviewed in the axial direction away from the annular upper surface of thelower casing base portion.

The thrust sliding bearing in accordance with the present invention ispreferably used as a thrust sliding bearing of a strut-type suspensionin a four-wheeled motor vehicle.

The synthetic resin for forming the upper casing and the lower casingmay be a thermoplastic synthetic resin such as polyacetal resin,polyamide resin, or polyester resin. In addition, the synthetic resinfor forming the thrust sliding bearing piece may be a thermoplasticsynthetic resin such as polyacetal resin, polyamide resin, polyolefinresin, or polyester resin. As the synthetic resin for forming the sealmember, it is possible to cite polyurethane as a preferred example.

Advantages of the Invention

According to the present invention, it is possible to provide a thrustsliding bearing which excels in the assembling efficiency andreplaceability, makes it possible to reduce the manufacturing cost, andis capable of further improving the durability and sealability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory cross-sectional view, taken in the direction ofarrow I-I shown in FIG. 3, of a preferred embodiment of the presentinvention;

FIG. 2 is an explanatory front elevational view of the embodiment shownin FIG. 1;

FIG. 3 is an explanatory plan view of the embodiment shown in FIG. 1;

FIG. 4 is an explanatory perspective view of the embodiment shown inFIG. 1;

FIG. 5 is an explanatory partially enlarged cross-sectional view of theembodiment shown in FIG. 1;

FIG. 6 an explanatory cross-sectional view of an upper casing of theembodiment shown in FIG. 1;

FIG. 7 is an explanatory partially enlarged cross-sectional view of theupper casing shown in FIG. 1;

FIG. 8 is an explanatory cross-sectional view, taken in the direction ofarrow VIII-VIII shown in FIG. 9, of a lower casing of the embodimentshown in FIG. 1;

FIG. 9 is an explanatory plan view of the lower casing of the embodimentshown in FIG. 1;

FIG. 10 is an explanatory perspective view of the lower casing of theembodiment shown in FIG. 1;

FIG. 11 is an explanatory cross-sectional view, taken in the directionof arrow XI-XI shown in FIG. 9, of the lower casing of the embodimentshown in FIG. 1;

FIG. 12 is an explanatory cross-sectional view, taken in the directionof arrow XII-XII shown in FIG. 7, of the lower casing of the embodimentshown in FIG. 1;

FIG. 13 is an explanatory partially enlarged plan view of the lowercasing of the embodiment shown in FIG. 1;

FIG. 14 is an explanatory cross-sectional view, taken in the directionof arrow XIV-XIV shown in FIG. 15, of a thrust sliding bearing piece ofthe embodiment shown in FIG. 1;

FIG. 15 is an explanatory plan view of the thrust sliding bearing pieceof the embodiment shown in FIG. 1;

FIG. 16 is an explanatory bottom view of the thrust sliding bearingpiece of the embodiment shown in FIG. 1;

FIG. 17 is an explanatory cross-sectional view, taken in the directionof arrow XVII-XVII shown in FIG. 15, of the thrust sliding bearing pieceof the embodiment shown in FIG. 1;

FIG. 18 is an explanatory view, taken in the direction of arrowXVIII-XVIII shown in FIG. 15, of the thrust sliding bearing piece of theembodiment shown in FIG. 1;

FIG. 19 is an explanatory front elevational view of a seal member of theembodiment shown in FIG. 1;

FIG. 20 is an explanatory front elevational view of the seal member ofthe embodiment shown in FIG. 1;

FIG. 21 is an explanatory bottom view of the seal member of theembodiment shown in FIG. 1;

FIG. 22 is an explanatory perspective view of a front side of the sealmember of the embodiment shown in FIG. 1;

FIG. 23 is an explanatory perspective view of a bottom side of the sealmember of the embodiment shown in FIG. 1; and

FIG. 24 is an explanatory view, taken in the direction of arrowXXIV-XXIV shown in FIG. 20, of the seal member of the embodiment shownin FIG. 1.

MODE FOR CARRYING OUT THE INVENTION

Hereafter, a more detailed description will be given of the presentinvention with reference to the preferred embodiment illustrated in thedrawings. It should be noted that the present invention is not limitedto the embodiment.

In FIGS. 1 to 5, a thrust sliding bearing 1 in accordance with thisembodiment for use in a strut-type suspension of a four-wheeled motorvehicle is comprised of a synthetic resin-made upper casing 2 which isfixed to a vehicle body side via a mounting member; a syntheticresin-made lower casing 3 which is superposed on the upper casing 2 soas to be rotatable about an axis O in a circumferential direction Rrelative to the upper casing 2 and is fixed to a spring seat side of acoil spring of the suspension; a synthetic resin-made thrust slidingbearing piece 5 disposed in an annular space 4 between the upper casing2 and the lower casing 3; and a synthetic resin-made seal member 8 forsealing respective other end portions, communicating with the outside,of a gap 6 on an inner peripheral side and a gap 7 on an outerperipheral side in a radial direction A between the upper casing 2 andthe lower casing 3, the gap 6 and the gap 7 respectively communicatingwith the annular space 4 at their one annular end portions.

As particularly shown in detail in FIGS. 5 to 7, the upper casing 2integrally includes an annular upper casing base portion 12 having anannular lower surface 11 in an axial direction B, an innerperipheral-side suspended cylindrical portion 14 suspended from an innerperipheral end portion 13 in a radial direction A of the annular lowersurface 11 of the upper casing base portion 12, an outer peripheral-sidesuspended cylindrical portion 16 suspended from an outer peripheral endportion 15 in the radial direction A of the annular lower surface 11 ofthe upper casing base portion 12, and an annular seat portion 18 formedprotrudingly on a central portion in the radial direction A of anannular upper surface 17 of the upper casing base portion 12.

The inner peripheral-side suspended cylindrical portion 14 has athick-walled cylindrical portion 22 connected at its upper end portion21 to the inner peripheral end portion 13 of the annular lower surface11 of the upper casing base portion 12, as well as a thin-walledcylindrical portion 27 which is connected at its upper end portion 23 toa lower end portion 26 of the thick-walled cylindrical portion 22 via aninner peripheral-side stepped annular surface 24 and an outerperipheral-side stepped annular surface 25 and is thinner-walledrelative to the thick-walled cylindrical portion 22.

The thick-walled cylindrical portion 22 and the thin-walled cylindricalportion 27 respectively have cylindrical inner peripheral surfaces 29and 30 which define a through hole 28 through which a shaft member of astrut-type suspension is inserted. The thick-walled cylindrical portion22 has a cylindrical outer peripheral surface 31, and the thin-walledcylindrical portion 27 has a cylindrical outer peripheral surface 32smaller in diameter than the outer peripheral surface 31.

The outer peripheral-side suspended cylindrical portion 16 having acylindrical outer peripheral surface 35 includes a cross-sectionallytrapezoidal cylindrical portion 38 which is connected at its upper endportion 36 to the outer peripheral end portion 15 of the annular lowersurface 11 of the upper casing base portion 12 and has an innerperipheral surface 37 which is gradually enlarged in diameter as viewedin a direction away from the annular lower surface 11 of the uppercasing base portion 12, as well as an enlarged cylindrical portion 42which is connected at its upper end portion 39 to a lower end portion 40of the cross-sectionally trapezoidal cylindrical portion 38 and has aninner peripheral surface 41 which is gradually reduced in diameter asviewed in a direction away from the lower end portion 40 of thecross-sectionally trapezoidal cylindrical portion 38 and is graduallyenlarged in diameter as viewed in a direction away from thisreduced-diameter end.

As particularly shown in detail in FIG. 5 and FIGS. 8 to 13, the lowercasing 3 integrally includes an annular lower casing base portion 52having an annular upper surface 51; an annular protrusion 53 protrudingfrom the annular upper surface 51 of the lower casing base portion 52toward the annular lower surface 11 of the upper casing base portion 12;an annular inner peripheral-side protrusion 57 protruding from theannular upper surface 51 toward the annular lower surface 11 of theupper casing base portion 12 on an inner peripheral side 56 of theannular upper surface 51 of the lower casing base portion 52 so as toform an inner peripheral-side annular recess 55 in cooperation with acylindrical inner peripheral surface 54 in the radial direction A of theannular protrusion 53; a hollow cylindrical portion 60 protruding froman inner peripheral portion 59 of an annular lower surface 58 of thelower casing base portion 52 so as to extend away from the annular lowersurface 58; an annular protruding portion 63 protruding inwardly from acylindrical inner peripheral surface 62 of the hollow cylindricalportion 60 at an end portion 61 of the hollow cylindrical portion 60; anannular protruding portion 64 protruding from the end portion 61 of thehollow cylindrical portion 60; and a plurality of projections 66 whichproject from an outer peripheral edge portion of an annular uppersurface 65 of the annular protrusion 53 toward the annular lower surface11 of the upper casing base portion 12 and are arranged along the outerperipheral edge portion of the annular upper surface 65 in such a manneras to be spaced apart from each other in the direction R about the axis(circumferential direction R).

The annular protrusion 53 includes an annular notched stepped portion 71at an outer peripheral portion of its upper surface 65; an annulararcuate recessed outer peripheral surface 73 which is connected at itslower end portion 72 to the outer peripheral end portion of the annularupper surface 51 of the lower casing base portion 52 and is graduallyreduced in diameter as viewed in a direction away from the annular uppersurface 51 of the lower casing base portion 52; a plurality of uppersurface grooves 74 arranged on its upper surface 65 by being spacedapart from each other at equal intervals in the circumferentialdirection R; and a plurality of inner peripheral surface grooves 75which are arranged on its inner peripheral surface 54 by being spacedapart from each other at equal intervals in the circumferentialdirection R in such a manner as to respectively communicate with theupper surface grooves 74 and also communicate with the innerperipheral-side annular recess 55.

The inner peripheral surface 62 of the hollow cylindrical portion 60 andan annular inner peripheral surface 76 of the protruding portion 63define a through hole 77 which is concentric with the through hole 28and through which the shaft member of the strut-type suspension isinserted.

As particularly shown in detail in FIG. 5 and FIGS. 14 to 18, thesynthetic resin-made thrust sliding bearing piece 5 disposed in theannular space 4 between the annular lower surface 11 of the upper casingbase portion 12 and the annular upper surface 51 of the lower casingbase portion 52 includes an annular radial bearing piece portion 83having an annular upper surface 81 which is brought into slidablecontact with the annular lower surface 11 of the upper casing baseportion 12 and an annular lower surface 82 which is brought into contactwith the upper surface 65 of the annular protrusion 53; a cylindricalaxial bearing piece portion 86 which is integrally formed at its one endportion on one end portion of the radial bearing piece portion 83 insuch a manner as to extend downwardly and has an annular inner sidesurface 84 which is brought into slidable contact with the outerperipheral surface 31 of the thick-walled cylindrical portion 22 and anannular outer side surface 85 which is brought into contact with theinner peripheral surface 54 of the annular protrusion 53; and aplurality of radial projecting plate piece portions 88 which projectoutwardly from an outer peripheral surface 87 of the radial bearingpiece portion 83, and which are respectively arranged between theprojections 66 in the circumferential direction R and clamped byadjacent ones of the projections 66 so that the thrust sliding bearingpiece 5 does not rotate in the circumferential direction R with respectto the lower casing 3.

The radial bearing piece portion 83 has an annular groove 91 provided onan inner peripheral side of the upper surface 81 and a plurality ofradial grooves 92 which are open at their one ends to the annular groove91 and is open at their other ends to the outer peripheral surface 87,and which are provided on the upper surface 81 by being spaced apart atequal intervals in the circumferential direction R. The axial bearingpiece portion 86 has a plurality of axial grooves 93 which are open attheir both ends and are provided on the inner side surface 84 by beingspaced apart at equal intervals in the circumferential direction R. Theaforementioned annular groove 91, radial grooves 92, and axial grooves93 serve as a lubricating oil sump.

As shown particularly in detail in FIGS. 19 to 24, the seal member 8 hason its inner peripheral side a flexible inner peripheral-side annularseal portion 103 which is elastically brought into flexural contact withthe outer peripheral surface 32 of the thin-walled cylindrical portion27 of the inner peripheral-side suspended cylindrical portion 14, so asto seal the gap 6 between the thin-walled cylindrical portion 27, i.e.,an axial end portion 101 of the inner peripheral-side suspendedcylindrical portion 14 of the upper casing 2, and the annular innerperipheral-side protrusion 57, i.e., an inner peripheral end portion 102of the lower casing base portion 52 of the lower casing 3, and has onits outer peripheral side a flexible outer peripheral-side annular sealportion 106 which is elastically brought into flexural contact with theinner peripheral surface 37 of the cross-sectionally trapezoidalcylindrical portion 38 of the outer peripheral-side suspendedcylindrical portion 16, so as to seal the gap 7 between an axial endportion 104 of the outer peripheral-side suspended cylindrical portion16 of the upper casing 2 and an outer peripheral end portion 105 of thelower casing base portion 52 of the lower casing 3. Further, the sealmember 8 has a plurality of connecting portions 107 for connecting theinner peripheral-side annular seal portion 103 and the outerperipheral-side annular seal portion 106 to each other.

Each of the plurality of connecting portions 107 which are arranged bybeing spaced apart from each other at equal intervals in thecircumferential direction R has a radial connecting portion 113 which isintegrally connected at its one end portion 111 to an annular innerperipheral end portion 112 of the outer peripheral-side annular sealportion 106, as well as an axial connecting portion 118 which isintegrally connected at its one end portion 114 to another end portion115 of the radial connecting portion 113 and at its other end portion116 to an annular outer peripheral end portion 117 of the innerperipheral-side annular seal portion 103.

Each of the plurality of connecting portions 107 is integrally connectedat its other end portion 116 to the inner peripheral-side annular sealportion 103 and at its one end portion 111 to the outer peripheral-sideannular seal portion 106 by being passed between the thrust slidingbearing piece 5 and the annular protrusion 53 of the lower casing 3 asthe radial connecting portion 113 is received by each of the uppersurface grooves 74 and the axial connecting portion 118 is received byeach of the inner peripheral surface grooves 75.

The inner peripheral-side annular seal portion 103 includes an annularinner peripheral seal base portion 131 which is integrally connected atits annular outer peripheral end portion 117 to an axial lower endportion, i.e., the other end portion 116, of the axial connectingportion 118 and which is fitted to the inner peripheral-side annularrecess 55, as well as a flexible inner peripheral seal portion 134 whichis connected at its outer peripheral end portion 132 to an innerperipheral end portion 133 of the inner peripheral seal base portion 131and which is elastically brought into flexural contact with the outerperipheral surface 32 of the thin-walled cylindrical portion 27 of theinner peripheral-side suspended cylindrical portion 14.

The inner peripheral seal portion 134 extends diagonally downwardly fromthe outer peripheral end portion 132 which has a smaller thickness thanthe thickness of the inner peripheral seal base portion 131 and which isconnected to the inner peripheral end portion 133 of the innerperipheral seal base portion 131.

The outer peripheral-side annular seal portion 106 includes an annularouter peripheral seal base portion 141 which is integrally connected atits annular inner peripheral end portion 112 to an outer lower endportion, i.e., the one end portion 111, of the radial connecting portion113 and which is fitted to the notched stepped portion 71, as well as aflexible outer peripheral seal portion 144 which is connected at itsinner peripheral end portion 142 to an outer peripheral end portion 143of the outer peripheral seal base portion 141 and is elastically broughtinto flexural contact with the inner peripheral surface 37 of thecross-sectionally trapezoidal cylindrical portion 38 of the outerperipheral-side suspended cylindrical portion 16.

The outer peripheral seal portion 144 extends diagonally downwardly fromthe inner peripheral end portion 142 which has a smaller thickness thanthe thickness of the outer peripheral seal base portion 141 and which isconnected to the outer peripheral end portion 143 of the outerperipheral seal base portion 141.

An upper surface 151 of the radial connecting portion 113 of theconnecting portion 107 is positioned flush with the upper surface 65 ofthe annular protrusion 53 of the lower casing 3 excluding the uppersurface grooves 74, and an inner side surface 152 of the axialconnecting portion 118 of the connecting portion 107 is positioned flushwith the inner peripheral surface 54 of the annular protrusion 53 of thelower casing 3 excluding the inner peripheral surface grooves 75. Thus,the radial bearing piece portion 83 at its lower surface 82 is incontact with the upper surface 65 of the annular protrusion 53 of thelower casing 3 and the upper surface 151 of the radial connectingportion 113 of the connecting portion 107, and the axial bearing pieceportion 86 at its outer side surface 85 is in contact with the innerperipheral surface 54 of the annular protrusion 53 of the lower casing 3and the inner side surface 152 of the axial connecting portion 118 ofthe connecting portion 107.

As an alternative to the above-described arrangement, the upper surface65 of the annular protrusion 53 of the lower casing 3 excluding theupper surface grooves 74 may be positioned higher than the upper surface151 of the radial connecting portion 113 of the connecting portion 107,and the inner peripheral surface 54 of the annular protrusion 53 of thelower casing 3 excluding the inner peripheral surface grooves 75 may bepositioned radially inwardly of the inner side surface 152 of the axialconnecting portion 118 of the connecting portion 107. In that case, theaxial bearing piece portion 83 at its lower surface 82 is in contactwith the upper surface 65 of the annular protrusion 53 of the lowercasing 3 while having a gap with the upper surface 151 of the radialconnecting portion 113 of the connecting portion 107, and the axialbearing piece portion 86 at its outer side surface 85 is in contact withthe inner peripheral surface 54 of the annular protrusion 53 of thelower casing 3 while having a gap with the inner side surface 152 of theaxial connecting portion 118 of the connecting portion 107.

The above-described thrust sliding bearing 1 is adapted to allow therelative rotation in the circumferential direction R of the lower casing3 with respect to the upper casing 2 by the relative sliding in thecircumferential direction R of each of the upper surface 81 of theradial bearing piece portion 83 with respect to the annular lowersurface 11 of the upper casing base portion 12 and the inner sidesurface 84 of the axial bearing piece portion 86 with respect to theouter peripheral surface 31 of the thick-walled cylindrical portion 22.

According to the above-described thrust sliding bearing 1, since each ofthe plurality of connecting portions 107 is integrally connected at itsone end portion to the inner peripheral-side annular seal portion 103and at its other end portion to the outer peripheral-side annular sealportion 106, the number of parts can be reduced, and the assemblingefficiency and the replaceability excel, making it possible to attain areduction in the manufacturing cost. Moreover, since each of theplurality of connecting portions 107 is passed between the thrustsliding bearing piece 5 and the annular protrusion 53 of the lowercasing 3, the durability can be improved by eliminating the possibilityof coming off.

In addition, according to the thrust sliding bearing 1, since the sealmember 8 has the inner peripheral-side annular seal portion 103 forsealing the gap 6 between the inner peripheral-side suspendedcylindrical portion 14 of the upper casing 2 and the inner peripheralend portion 102 of the lower casing 3 and the outer peripheral-sideannular seal portion 106 for sealing the gap 7 between the outerperipheral-side suspended cylindrical portion 16 of the upper casing 2and the outer peripheral end portion 105 of the lower casing 3, thesealability can be further improved.

DESCRIPTION OF REFERENCE NUMERALS

-   1: thrust sliding bearing-   2: upper casing-   3: lower casing-   4: annular space-   5: thrust sliding bearing piece-   6, 7: gap-   8: seal member

1. A thrust sliding bearing comprising: a synthetic resin-made uppercasing integrally including an annular upper casing base portion havingan annular lower surface in an axial direction, an inner peripheral-sidesuspended cylindrical portion suspended from a radial inner peripheralend portion of the annular lower surface of the upper casing baseportion, and an outer peripheral-side suspended cylindrical portionsuspended from a radial outer peripheral end portion of the annularlower surface of the upper casing base portion; a synthetic resin-madelower casing integrally including an annular lower casing base portionhaving an annular upper surface in the axial direction and superposed onsaid upper casing so as to be rotatable about an axis relative to saidupper casing and an annular protrusion protruding from the annular uppersurface of the lower casing base portion toward the annular lowersurface of the upper casing base portion; a synthetic resin-made thrustsliding bearing piece disposed in an annular space between the annularlower surface of the upper casing base portion and the annular uppersurface of the lower casing base portion, so as to be brought at anaxial annular upper surface and a radial cylindrical inner peripheralsurface thereof into slidable contact with the annular lower surface ofthe upper casing base portion and a radial outer peripheral surface ofthe inner peripheral-side suspended cylindrical portion, while beingbrought at an axial annular lower surface and a radial cylindrical outerperipheral surface thereof into contact with an axial annular uppersurface and a radial cylindrical inner peripheral surface of the annularprotrusion; and a synthetic resin-made seal member having on a radialinner peripheral side thereof a flexible inner peripheral-side annularseal portion which is brought into contact with a radial innerperipheral surface of the inner peripheral-side suspended cylindricalportion of the upper casing so as to seal a gap between the innerperipheral-side suspended cylindrical portion of said upper casing andthe lower casing base portion of said lower casing, having on a radialouter peripheral side thereof a flexible outer peripheral-side annularseal portion which is brought into contact with an radial innerperipheral surface of the outer peripheral-side suspended cylindricalportion of said upper casing so as to seal a gap between the outerperipheral-side suspended cylindrical portion of said upper casing andthe lower casing base portion of said lower casing, and having aplurality of connecting portions arranged by being spaced apart fromeach other in a direction about the axis, so as to connect to each otherthe inner peripheral-side annular seal portion and the outerperipheral-side annular seal portion, wherein each of the plurality ofconnecting portions is passed between said thrust sliding bearing pieceand the annular protrusion of said lower casing and is integrallyconnected at one end portion thereof to the inner peripheral-sideannular seal portion and at another end portion thereof to the outerperipheral-side annular seal portion.
 2. The thrust sliding bearingaccording to claim 1, wherein each of the connecting portions of saidseal member has a radial connecting portion which is integrallyconnected at one radial end portion thereof to the outer peripheral-sideannular seal portion and an axial connecting portion which is integrallyconnected at one axial end portion thereof to another radial end portionof the radial connecting portion and at another axial end portionthereof to the inner peripheral-side annular seal portion, wherein theannular protrusion of said lower casing has upper surface grooves whichare arranged on an axial upper surface thereof by being spaced apartfrom each other in a direction about the axis and receive respectiveones of the radial connecting portions of the connecting portions andinner peripheral surface grooves which are arranged on a radial innerperipheral surface thereof by being spaced apart from each other in thedirection about the axis and connected to respective ones of the uppersurface grooves and receive respective ones of the axial connectingportions of the connecting portions, wherein the upper surface of theannular protrusion of the lower casing excluding the upper surfacegrooves is positioned flush with or higher than an axial upper surfaceof the radial connecting portion of the connecting portion, and theinner peripheral surface of the annular protrusion of the lower casingexcluding the inner peripheral surface grooves is positioned flush withor radially inwardly of a radial inner side surface of the axialconnecting portion of the connecting portion, and wherein said thrustsliding bearing piece has a radial bearing piece portion which is incontact with the upper surface of the annular protrusion of the lowercasing and an axial bearing piece portion which is in contact with theinner peripheral surface of the annular protrusion of the lower casing.3. The thrust sliding bearing according to claim 1, wherein the annularprotrusion has an annular notched stepped portion on a radial outerperipheral portion of the upper surface thereof, and the flexible outerperipheral-side annular seal portion has an annular outer peripheralseal base portion which is integrally connected at a radial innerperipheral end portion thereof to a radial outer end portion of theradial connecting portion and is fitted to the notched stepped portionand a flexible outer peripheral seal portion which is connected at aradial inner peripheral end portion thereof to a radial outer peripheralend portion of the outer peripheral seal base portion and is broughtinto contact with an inner peripheral surface of the outerperipheral-side suspended cylindrical portion of said upper casing. 4.The thrust sliding bearing according to claim 1, wherein said lowercasing has integrally with the lower casing base portion an annularinner peripheral-side protrusion protruding from a radial innerperipheral portion of the annular upper surface of the lower casing baseportion toward an annular lower surface of the upper casing base portionso as to form an inner peripheral-side annular recess in cooperationwith the inner peripheral surface of the annular protrusion, and theinner peripheral-side annular seal portion has an annular innerperipheral seal base portion which is integrally connected at a radialouter peripheral end portion thereof to an axial lower end portion ofthe axial connecting portion and which is fitted to the innerperipheral-side annular recess, as well as a flexible inner peripheralseal portion which is connected at a radial outer peripheral end portionto a radial inner peripheral end portion of the inner peripheral sealbase portion and which is brought into contact with the outer peripheralsurface of the inner peripheral-side suspended cylindrical portion ofsaid upper casing.